1. Field of the Invention
The present invention relates to a liquid jet head for discharging a desired liquid by the creation of air bubbles brought about by causing thermal energy to act upon liquid, a head cartridge using the liquid jet head, a liquid jet apparatus, and a liquid discharging method. The invention also relates to an ink jet kit provided with the liquid jet head.
More particularly, the invention relates to a liquid jet head having movable members capable of being displaced by the utilization of the creation of air bubbles. It also relates to a head cartridge using the liquid jet head, and a liquid jet apparatus.
The present invention is also applicable to a printer for recording on a recording medium, such as paper, thread, fabric, cloth, leather, plastic, glass, wood, or ceramics, and also, to a copying machine, a facsimile equipment provided with communication systems, a word processor or other apparatuses having a printing unit therefor. Further, the present invention is applicable to a recording system for industrial use, which is complexly combined with various processing apparatuses.
Here, the term "recording" in the description of the present invention means not only the provision of images having characters, graphics, or other meaningful representation, but only the provision of those images that do not present any meaning, such as patterns.
2. Related Background Art
There has been known the so-called bubble jet recording method, which is an ink jet recording method whereby to form images on a recording medium by discharging ink from discharge ports using acting force exerted by the change of states of ink brought about by the abrupt voluminal changes (creation of air bubbles) when thermal energy or the like is applied to ink in accordance with recording signals. For the recording apparatus that uses the bubble jet recording method, it is generally practiced to provide, as disclosed in the specifications of U.S. Pat. No. 4,723,129 and others, the discharge ports that discharge ink, the ink paths conductively connected to the discharge ports, and electrothermal transducing elements arranged in each of the ink paths as means for generating energy for discharging ink. Then, it is generally practiced for the bubble jet recording method that the air bubbles are developed by means of film boiling generated in liquid.
In accordance with such recording method, it is possible to record high quality images at high speeds with a lesser amount of noises. At the same time, the head that executes this recording method makes it possible to arrange the discharge ports for discharging ink in high density, with the advantage, among many others, that images are recordable in high resolution, and that color images are easily obtainable by use of a smaller apparatus. In recent years, therefore, the bubble jet recording method is widely adopted for many kinds of office equipment, such as a printer, a copying machine, a facsimile equipment. Further, this recording method is utilized even for industrial systems, such as a textile printing, among others.
Along the wider utilization of bubble jet technologies and techniques for various products in many different fields, there have been increasingly more demands technically in recent years as given below.
For example, as to the demand on the improvement of energy efficiency, the adjustment of the thickness of protection film has been studied to optimize the performance of heat generating elements. A study of the kind has produced effects on the enhancement of transfer efficiency of generated heat to liquids. Also, in order to obtain high quality images, there has been proposed a driving condition under which a liquid discharging method or the like is arranged to be able to execute good ink discharges at higher ink discharging speeds with more stabilized creation of air bubbles. Also, from the viewpoint of a high-speed recording, there has been proposed the improved configuration of liquid flow paths that makes it possible to obtain a liquid jet head capable of refilling liquid to the liquid flow paths at higher speeds after discharging.
Of the various configurations of liquid flow paths thus proposed, those represented in FIGS. 22A and 22B are disclosed in the specification of Japanese Patent Laid-Open Application No. 63-199972 as a liquid flow path structure. The liquid flow path structure and a method for manufacturing heads disclosed in the specification thereof are the inventions devised with attention to the back waves (the pressure orientated opposite to the direction toward the discharge ports, that is, pressure exerted in the direction toward the liquid chamber 12). The back waves are known as energy loss because such energy is not exerted in the discharging direction.
FIGS. 22A and 22B illustrate valves 10, each arranged away from the air bubble generating area of the heat generating element 2, and positioned in the side opposite to the discharge port 11 with respect to the heat generating element 2. It is disclosed that the valve 10 keeps its initial position as being adhesively bonded to the ceiling of the liquid flow path 3 by means of a method of manufacture utilizing a plate material or the like, and falls down inside the liquid flow path 3 along the creation of the air bubble as represented in FIG. 22B. It is further disclosed that the invention relates to a method for suppressing the energy loss by controlling the back waves described above partly by the arrangement of the valves 10.
However, in accordance with the disclosed structure, even if the back waves are partly controlled by means of valves 10 for the suppression thereof, it is not necessarily sufficient to enhance the capability of liquid discharge. This is clearly understandable from studies on the condition under which the air bubbles are created in the liquid flow path 3 that retains in it liquid to be discharged.
Fundamentally, the back waves themselves are not related directly with discharging as described earlier. Of the components of pressure exerted by each air bubble, those directly related with discharge have already acted upon liquid to be in the state of being discharged from the liquid flow path 3 the moment the back waves are generated in the flow path 3 as indicated in FIG. 22B. Therefore, even if the back waves are suppressed, it is difficult to provide a sufficient contribution to enhancing the discharging performance, notwithstanding its partial suppression as described above.
The applicant hereof has already filed an application for a patent based on a completely new invention for positively controlling air bubbles in order to enhance the fundamental discharging properties to such a high level that has never been anticipated in the conventional art by giving light upon the aspects that have not been considered with respect to the conventional method for discharging liquid by the creation of air bubbles (particularly, those following film boiling) in each of the liquid flow paths. In accordance with this invention, the positive control of air bubbles is made possible by arranging the positional relationship between the fulcrum and free end of each movable member in such a manner that the free end thereof is positioned on the discharge port side, that is, on the downstream side, and also, by arranging each of the movable members in a position to face the air bubble generating area.
With the knowledge that the developing component of the air bubble on the downstream side should be altered and effectively directed to the discharging side in consideration of the developing component of the air bubble on the downstream side, and that this directional change of such component should only bring about the enhancement of the discharging efficiency and discharging speeds, the present invention is designed to shift the developing component of the air bubble on the downstream side to the free end side of the movable member positively. Therefore, it is required to apply an art of extremely high standard to the implementation thereof as compared with the level of the conventional technologies and techniques in this field.
With such technical background as described above, the inventor et al hereof have found further that it is possible to reduce the load more at the time of initiating the displacement of the movable member by adjusting the condition of the free end of the movable member before the creation of the air bubble in consideration of the function of the movable member when its displacement is initiated.
With the knowledge thus obtained, the inventor et al hereof have found the excellent principle of liquid discharge. Thus, in accordance with such discharging principle, the present invention has been made.
The prime objective of the invention is given below.
It is a first object of the invention to provide the principle of liquid discharge, which is quite new with respect to the fundamental control of created air bubbles.
It is a second object of the invention to provide a liquid discharging method capable of discharging liquid in good condition, a liquid jet head, and others.
It is a third object of the invention to provide a liquid jet head and others operative at increased printing speed or the like by suppressing the inertial force exerted by back waves, which acts in the direction opposite to the direction of liquid supply, and at the same time, by reducing the regressive amount of meniscus using the valve function of each movable member for the enhancement of refilling frequency.
It is a fourth object of the invention to provide a liquid jet head or the like having a sufficiently high discharging efficiency and discharging power to facilitate the valve opening and closing operations at the time of initiating the discharge operation for a pattern recording that necessitates the repetition of recording required for its initial operation, and frequent discharge and suspension as well.
It is a fifth object of the invention to provide a head kit to facilitate the reuse of the liquid jet head of the present invention.